How many ways are there to put 4 indistinguishable balls into 2 indistinguishable boxes?
Solution: In this problem, we only need to count the number of ways to split 4 items into two groups.  There are only 3 ways: $\{4,0\}$, $\{3,1\}$ and $\{2,2\}$.  Therefore, there are only $\boxed{3}$ ways to put 4 indistinguishable balls in 2 indistinguishable boxes.